Steer clear of the Revell>Monogram>Aurora kits, if you're looking to build models accurate in the sense of incorporating serious paleontological data. Same goes for the old Lindberg kits, which I think were originally by Life-Like. I built those as a kid, and while they're fun, especially to a 7-year-old crazy about dinosaurs, they're not really good kits, whether we consider accuracy or the quality of the kits.
I can't speak to the later Lindberg kits, which were produced in the wake of the relase of "Jurassic Park", if I'm not mistaken. But I think they incorporate the more recent interpretation of the fossil record (as an aside, the "more recent interpretation" actually includes an older interpretation. In the latter half of the 19th century, the idea that dinosaurs were active, agile creatures was quite current. Only later, in the 20s and 30s, did the view of them as big, lumbering, swamp-dwelling, tail-draggin lizards gain the upper hand).
I'll second AJ about the Tamiya kits, especially the newer ones. I have the later T-Rex kit, and it's a good kit. I'm not going to build it as the sprinting Rex, because I think Horner's interpretaion is more likely than Bakker's, but it looks like more modern museum models that I've seen, than Tamiya's older tail-dragger. And it includes a figure, too. You can make a little JP dio, or use him someplace else.
Also, if you'd like to see some excellent resin kits, have a look at Link and Pin Hobbies' site, and their dino kit page:
http://www.linkandpinhobbies.com/Dino.htm
Though be forewarned-these kits can be pricey. But you'll find subjects not tackled by the styrene makers, including theropods other than T-Rex, horned dinos other than Triceratops, and the marine and flying reptiles.
Hope that helps!
Brad